Bulk and Surface Effects on Blood Compatibility

Abstract

Studies on protein adsorption and platelet adhesion indicate that polymer surfaces can selectively adsorb proteins from whole blood in vivo and the composition of this adsorbed protein layer influences the adhesion of plate lets, and thus determines the thrombogenicity of the polymer. The microphase structure of the block copolyurethanes seems to often confer a selectivity in albumin adsorption, which appears to make these materials relatively non- thrombogenic Analyses of the synthetic procedures for preparing these block copolyurethanes have indicated that the standard two-step synthetic procedure introduces sizeable amounts of dimeric soft and hard segments into the copoly mers. FT-IR and ESCA are being used to determine the bulk and surface mor phology of these standard block copolyurethanes as well as their pure (AB)_n analogs, so as to understand protein binding to their surfaces. A study of these materials as vascular grafts has indicated that the bulk properties (i.e., the compliance of the graft) can also affect graft patency under in vivo conditions.